The present disclosure is directed to a semiconductor memory device and a method of forming the same, and more particularly, to a nonvolatile memory device and a method of forming the same.
Generally, semiconductor memory devices may be classified into volatile memory devices and nonvolatile memory devices. Volatile memory devices lose stored data when powered off, whereas nonvolatile memory devices retain stored data even when powered off. Flash memory devices, which are nonvolatile memory devices, are highly integrated devices developed by combining Erasable Programmable Read Only Memories (EPROM) that are programmable and erasable with Electrically Erasable Programmable Read Only Memories (EEPROM) that are electrically programmable and erasable.
Flash memory devices may have structures in which a floating gate for storing data and a control gate for controlling the floating gate are sequentially stacked. The structure may hinder down-scaling of a memory device because of the vertical height of the floating gate. Accordingly, flash memory devices using a charge trap layer are being developed to not only reduce the vertical height of a memory cell and but also to maintain retention characteristics for long-lasting maintenance of stored data.